Truss plates are generally employed to join planks of lumber that form floor and roof trusses used in residential housing. Truss plates typically comprise a backing plate and an array of sharp spike-like impaling members that extend outwardly from one side of the backing plate. Adjacent planks of a truss with coplanar surfaces can be permanently joined by pounding or pressing the backing member of a truss plate so that its impaling members penetrate the planks.
In the past truss plates were typically packaged in boxes or cartons in no particular order whatsoever; they were simply strewn haphazardly within their container. If the container were emptied or if it were somehow removed or destroyed, the truss plates would spill and spread and were quite hazardous until they were retrieved and restored. As a result, truss plates were generally stored on-site in their packaging cartons until use.
As a solution to this problem, U.S. Pat. No. 5,392,908 to Black describes a truss plate packaging method and configuration in which truss plates are packaged in unitized bundles. The truss plates are arranged so that their respective backing members are substantially parallels with the peripheries of the backing members being substantially aligned. The truss plates are then interconnected with some interconnecting means, such as a strap that snugly wraps around the truss plates, to form a unitized bundle. Such a bundle can be conveniently shipped, stored, and handled in the manufacture of trusses.
A manufacturing apparatus for bundling truss plates in this manner is illustrated and described in U.S. Pat. No. 5,636,494 to Black (hereinafter the '494 patent), the disclosure of which is hereby incorporated herein in its entirety. This apparatus receives four truss plates as they exit a punch press. The plates are disposed horizontally and travel to a pair of horizontal shelves. They fall from either side of the shelves into four receiving channels that orient them generally vertically. These channels convey the truss plates to retractable stops, which halt the forward motion of the truss plates until all four truss plates are present. The stops are positioned so that, as the truss plates rest against them, the perimeters of the truss plates are substantially aligned. Retraction of the stops causes a pairing mechanism to direct the truss plates into two cooperating pairs, in which the impaling members of one truss plate of the pair extend toward the backing member of the other truss plate of the pair. The two cooperating pairs of truss plates are then conveyed to a receiving chamber, where they are stacked with other sets of cooperating pairs until a predetermined number of truss plates has been accumulated. The stacked truss plates are then conveyed as a stack to a banding station, where a plastic band is wrapped around the stack to form a truss plate bundle. Each truss plate bundle travels to an accumulation stage, from where a preselected number of truss plate bundles is gripped between a pair of elongate plates and lifted onto a pallet. This process continued until the pallet is filled with truss plate bundles. This manufacturing system has proven to be successful in automatically producing truss plate bundles.
Although this manufacturing system is satisfactory for the packaging of many truss plates, the system as illustrated may be unsatisfactory for orientating of wide truss plates. The system illustrated in the '494 patent is designed to receive four truss plates as they are formed simultaneously at the punch press from a single strip of steel. A pair of truss plates falls from each side of each shelf, so that their impaling members extend toward the other plate of the pair. This configuration is suitable for 3 inch wide truss plates, which can be formed from a 12 inch strip of steel, but may be less suitable for wider truss plates, such as 7, 8, or 9 inch wide truss plates. These wider truss plates are typically formed at the punch press one at a time from 7, 8, or 9 inch wide strips of steel (wider strip steel is less readily available). Thus, a system is needed to orient truss plates typically formed in a single stream of truss plates (i.e., wider than 6 inches).